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#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "edf.h"
long maxlockcycles;
long maxilockcycles;
long cumlockcycles;
long cumilockcycles;
ulong maxlockpc;
ulong maxilockpc;
struct
{
ulong locks;
ulong glare;
ulong inglare;
} lockstats;
static void
inccnt(Ref *r)
{
_xinc(&r->ref);
}
static int
deccnt(Ref *r)
{
int x;
x = _xdec(&r->ref);
if(x < 0)
panic("deccnt pc=%#p", getcallerpc(&r));
return x;
}
static void
dumplockmem(char *tag, Lock *l)
{
uchar *cp;
int i;
iprint("%s: ", tag);
cp = (uchar*)l;
for(i = 0; i < 64; i++)
iprint("%2.2ux ", cp[i]);
iprint("\n");
}
void
lockloop(Lock *l, ulong pc)
{
Proc *p;
p = l->p;
print("lock %#p loop key %#lux pc %#lux held by pc %#lux proc %lud\n",
l, l->key, pc, l->pc, p ? p->pid : 0);
dumpaproc(up);
if(p != nil)
dumpaproc(p);
}
int
lock(Lock *l)
{
int i;
ulong pc;
pc = getcallerpc(&l);
lockstats.locks++;
if(up)
inccnt(&up->nlocks); /* prevent being scheded */
if(tas(&l->key) == 0){
if(up)
up->lastlock = l;
l->pc = pc;
l->p = up;
l->isilock = 0;
#ifdef LOCKCYCLES
l->lockcycles = -lcycles();
#endif
return 0;
}
if(up)
deccnt(&up->nlocks);
lockstats.glare++;
for(;;){
lockstats.inglare++;
i = 0;
while(l->key){
if(conf.nmach < 2 && up && up->edf && (up->edf->flags & Admitted)){
/*
* Priority inversion, yield on a uniprocessor; on a
* multiprocessor, the other processor will unlock
*/
print("inversion %#p pc %#lux proc %lud held by pc %#lux proc %lud\n",
l, pc, up ? up->pid : 0, l->pc, l->p ? l->p->pid : 0);
up->edf->d = todget(nil); /* yield to process with lock */
}
if(i++ > 100000000){
i = 0;
lockloop(l, pc);
}
}
if(up)
inccnt(&up->nlocks);
if(tas(&l->key) == 0){
if(up)
up->lastlock = l;
l->pc = pc;
l->p = up;
l->isilock = 0;
#ifdef LOCKCYCLES
l->lockcycles = -lcycles();
#endif
return 1;
}
if(up)
deccnt(&up->nlocks);
}
}
void
ilock(Lock *l)
{
ulong x;
ulong pc;
pc = getcallerpc(&l);
lockstats.locks++;
x = splhi();
if(tas(&l->key) != 0){
lockstats.glare++;
/*
* Cannot also check l->pc, l->m, or l->isilock here
* because they might just not be set yet, or
* (for pc and m) the lock might have just been unlocked.
*/
for(;;){
lockstats.inglare++;
splx(x);
while(l->key)
;
x = splhi();
if(tas(&l->key) == 0)
goto acquire;
}
}
acquire:
m->ilockdepth++;
if(up)
up->lastilock = l;
l->sr = x;
l->pc = pc;
l->p = up;
l->isilock = 1;
l->m = MACHP(m->machno);
#ifdef LOCKCYCLES
l->lockcycles = -lcycles();
#endif
}
int
canlock(Lock *l)
{
if(up)
inccnt(&up->nlocks);
if(tas(&l->key)){
if(up)
deccnt(&up->nlocks);
return 0;
}
if(up)
up->lastlock = l;
l->pc = getcallerpc(&l);
l->p = up;
l->m = MACHP(m->machno);
l->isilock = 0;
#ifdef LOCKCYCLES
l->lockcycles = -lcycles();
#endif
return 1;
}
void
unlock(Lock *l)
{
#ifdef LOCKCYCLES
l->lockcycles += lcycles();
cumlockcycles += l->lockcycles;
if(l->lockcycles > maxlockcycles){
maxlockcycles = l->lockcycles;
maxlockpc = l->pc;
}
#endif
if(l->key == 0)
print("unlock: not locked: pc %#p\n", getcallerpc(&l));
if(l->isilock)
print("unlock of ilock: pc %lux, held by %lux\n", getcallerpc(&l), l->pc);
if(l->p != up)
print("unlock: up changed: pc %#p, acquired at pc %lux, lock p %#p, unlock up %#p\n", getcallerpc(&l), l->pc, l->p, up);
l->m = nil;
l->key = 0;
coherence();
if(up && deccnt(&up->nlocks) == 0 && up->delaysched && islo()){
/*
* Call sched if the need arose while locks were held
* But, don't do it from interrupt routines, hence the islo() test
*/
sched();
}
}
ulong ilockpcs[0x100] = { [0xff] = 1 };
static int n;
void
iunlock(Lock *l)
{
ulong sr;
#ifdef LOCKCYCLES
l->lockcycles += lcycles();
cumilockcycles += l->lockcycles;
if(l->lockcycles > maxilockcycles){
maxilockcycles = l->lockcycles;
maxilockpc = l->pc;
}
if(l->lockcycles > 2400)
ilockpcs[n++ & 0xff] = l->pc;
#endif
if(l->key == 0)
print("iunlock: not locked: pc %#p\n", getcallerpc(&l));
if(!l->isilock)
print("iunlock of lock: pc %#p, held by %#lux\n", getcallerpc(&l), l->pc);
if(islo())
print("iunlock while lo: pc %#p, held by %#lux\n", getcallerpc(&l), l->pc);
sr = l->sr;
l->m = nil;
l->key = 0;
coherence();
m->ilockdepth--;
if(up)
up->lastilock = nil;
splx(sr);
}
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